80 SEX 



ance finds expression or not may depend on 

 whether the organism is male or female in 

 its fundamental metabolism; and similarly 

 what degree of expression a particular char- 

 acter finds opportunity for in development 

 may be determined in the same way. 



THE ROLE OF INTERNAL SECRETIONS. It 

 has long been recognised that the reproductive 

 organs exert a pervasive influence on the 

 body, as is conspicuously seen in the changes 

 that occur at adolescence, and in pregnancy, 

 even in remote parts of the body. The fact 

 is expressed in Helmont's aphorism : " Propter 

 solum uterum mulier est, quod est," which 

 Chereau changed into " Propter solum ovarium 

 mulier est, quod est." 



The view of Pfliiger, that the gonads exert 

 an influence through the nerves associated 

 with them has given place to the view, 

 originating with Brown-Sequard, that the 

 influence passes into the body by the medium 

 of the internal secretions of the gonads. To 

 Starling we owe the convenient term " hor- 

 mones " for the specific stimulating sub- 

 stances in these internal secretions, and more 

 recently Schafer has given convincing illus- 

 trations of their subtle and multifarious 

 efficacy within the organism. 



It may be explained that a male organ or 

 testis in a higher animal consists of sperm- 

 making cells arranged in tubules, of inter- 

 stitial cells of various types, the whole within 

 an outer envelope of connective tissue. Simi- 

 larly the female organ or ovary consists of 

 ova disposed in groups of follicles, ' of inter- 

 stitial cells of various kinds (the stroma of 



